Protists-rhizarians, Red & Green Algae, Unikonts

This is a very diverse group of organisms that DNA evidence suggests a monophyletic group.

What characterizes an amoeba, a large group in the Rhizara clade?

Amoebas are mobile.Feed via pseudopodia (extensions that bulge from the cell surface)

Note: there are amoebas that belong to other eukaryotic taxa but most fall within this group.

What characterizes forams?

Protists with porous shells called testsHave pseudopodia that help them move & feedFound in both fresh and marine waters, sand, attached to rock or algae.Most are known from fossils

What characterizes radiolarians?

Have delicate intricate symmetrical internal skeltons made of silicaMostly marinePsuedopodia radiate from central body, reinforced by microtubules which are covered by a thin layer of cytoplasm.

What groups make up the supergroup Archaeplastida?

Red algaeGreen algae and land plants

What characterizes red algae?

Are reddish in hue due to phycoerythrin (masks chlorophyll-can range in color depending on location).Most abundant large algae in warm coastal tropical waters (some freshwater and land species)Usually multicellularVery diverse life cycles-alteration of generations is common but don't have flagellated stages like most algae

Describe the characteristics of green algae.

Chloroplasts are ultra structured-like those of land plantsClosely related to land plants2 groups: Chlorophytes Charophytes

What characterizes the green algae subgroup, Chlorophytes?

Most freshwater, some marine & land speciesRange from single-celled to complex multi-cellular.Some live symbiotically with other eukaryotesLarger size& complexity arose from 3 mechs.

This is a newly proposed divers group of eukarya that includes animals, fungi, and some protists.The protists in this group include amoebozoans and opisthokonts.

Describe the subgroup Amoebozoans.

This is a clade that includes many species of amoebas (those not part of Rhizaria group)Includes:Slime molds

plasmodial -bright, mostly diploid in life cycle, form supercells

cellular- mostly haploid in life cycle, remain normal single cells even when they aggregate

Gymnamoebas- Most are heterotrophic, found in most environmentsEntomoebas-parasitic, many cause amoebic dysentery

Describe the Opisthokonts.

These are very diverse -inlcudes animals, fungi and several groups of protists. The protists in this group are more closely related to animals or fungi so share more of their traits.

Describe the importance of symbiotic and photosynthetic protists in ecological terms.

Many ecosystems, such as coral reefs, rely on the symbiotic relationship of certain species with certain protists. Without these relationships, most ecosystems would fail affecting all levels of life. Photosynthetic protists are major producers for their ecosystems, especially in marine environments. Make up about 1/4 the world's photosynthesis.